Coloboma
Understanding Coloboma
During the early weeks of pregnancy, the eye develops from a structure that starts as an open cup and then closes along a seam called the optic fissure. A coloboma happens when this seam does not close completely by the seventh week of development. This leaves a gap in one or more parts of the eye where tissue is missing or did not form fully.
This gap is not something that happens after birth or develops over time. Your child is born with the condition, though it may not always be noticed immediately if the affected area is at the back of the eye rather than visible from the outside.
A coloboma can occur in several different structures within the eye. The iris, which is the colored part of your eye, is often affected and creates a visible keyhole shape in the pupil. The retina, which is the light-sensitive layer at the back of your eye, can also have missing tissue. Because the embryonic fissure lies inferonasally, most ocular colobomas are located in the lower inner quadrant of the eye.
- The choroid, a layer of blood vessels beneath the retina
- The ciliary body and zonules, which support the lens
- The optic nerve, which carries visual signals to your brain
- The lens, most often appearing as a notch due to missing zonules rather than missing lens tissue
An eyelid coloboma is a gap in the eyelid, not a defect within the eye itself. It arises from different developmental processes and can cause exposure of the cornea, dryness, and irritation.
Management focuses on lubrication and surgical repair to protect the ocular surface.
We classify colobomas based on which part of the eye is affected. An iris coloboma is the most visible type and gives the pupil a keyhole or cat-eye appearance. A chorioretinal coloboma affects the retina and choroid at the back of the eye and may significantly impact central or peripheral vision. Uveal coloboma can involve the iris, ciliary body, choroid, and retina. Lens coloboma usually reflects a zonular-ciliary body defect that creates a lens notch rather than true absence of lens tissue.
Optic nerve colobomas involve the area where the optic nerve meets the eye and can cause serious vision problems. Some people have more than one type, and the severity can vary greatly from one person to another.
The impact on vision depends entirely on the location and size of the gap. A small iris coloboma may cause only light sensitivity with near-normal vision, while a large retinal or optic nerve coloboma can result in significant vision loss. If the central part of the retina called the macula is affected, reading and recognizing faces become difficult. When the retina is involved, visual field defects or blind spots can occur that may not be obvious without testing.
Some children with coloboma have vision that is good enough for most daily activities, while others may be legally blind in the affected eye. We assess each case individually because no two colobomas are exactly alike.
Recognizing the Signs of Coloboma
The most recognizable sign of coloboma is an unusually shaped pupil that looks like a keyhole or an upside-down teardrop. This occurs when the iris has a gap, typically in the lower portion. The pupil may appear normal in dim light but shows the keyhole shape more clearly in bright conditions.
You might also notice that one eye looks different from the other if only one eye is affected. In some cases, the eye may be smaller than normal, a condition called microphthalmia that can occur alongside coloboma.
Children with coloboma may squint frequently or have trouble seeing in bright light. They might hold books very close to their face or sit unusually close to the television. Poor depth perception and difficulty with tasks requiring fine visual detail, like threading beads or coloring within lines, can also be signs.
- Sensitivity to bright lights and glare
- Reduced ability to see objects to one side
- Blurred or decreased vision in one or both eyes
- Difficulty adjusting when moving between bright and dim environments
- Eye misalignment (strabismus) or a consistent head turn or tilt
Very young children cannot tell you they have vision problems, so we rely on observation. An infant with coloboma might not track moving objects well or may not make eye contact consistently. You might notice that your baby does not react to visual cues like smiles or toys at the expected distance. New or persistent eye crossing or drifting after 4 to 6 months of age also warrants evaluation.
Some babies develop involuntary eye movements called nystagmus, where the eyes move side to side or up and down on their own. This often indicates reduced vision and should prompt evaluation by a pediatric ophthalmologist.
Certain symptoms require urgent attention. If your child suddenly complains of seeing flashes of light, a curtain or shadow blocking part of their vision, a sudden increase in floating spots, sudden severe eye pain with headache, halos, or nausea, or eye injury, contact us right away. These can be signs of retinal detachment, which people with retinal coloboma face a higher risk of developing.
Any new onset of pain, redness, or significant vision loss in an eye with coloboma also warrants immediate evaluation. Early intervention can make a critical difference in preserving whatever vision remains. If you have vision in only one functioning eye, any new symptoms in that eye require urgent assessment.
What Causes Coloboma and Who Is at Risk
Many cases of coloboma occur due to genetic changes that affect eye development. Some colobomas are inherited from a parent in an autosomal dominant pattern, which means if one parent has the gene change, each child has a 50 percent chance of inheriting it. However, even with the same genetic change, the severity can vary widely among family members.
Other genetic patterns are also possible, including autosomal recessive and X-linked inheritance. In many cases, coloboma appears to happen spontaneously with no family history, caused by a new genetic change in the affected individual. Specific syndromes include renal coloboma syndrome and others, so targeted evaluation is often recommended.
Certain factors during pregnancy may increase the risk of coloboma, though the exact cause often remains unknown. Exposure to alcohol during early pregnancy has been associated with eye malformations including coloboma. Some infections during pregnancy and certain medications may also play a role, though these connections are not always clear.
- Maternal diabetes that is not well controlled
- Exposure to certain chemicals or toxins
- Vitamin A deficiency during critical developmental periods
- Use of certain prescription medications during the first trimester
Most cases are sporadic and not caused by anything a parent did or did not do. Do not stop prescription medications during pregnancy without discussing risks and benefits with your obstetric and prescribing clinicians.
Coloboma can occur by itself, affecting only the eye, or it can be part of a syndrome involving other organs and systems. CHARGE syndrome is one of the more common syndromes associated with coloboma and includes heart defects, growth delays, ear abnormalities, and other features. Cat eye syndrome, caused by an extra piece of chromosome 22, also frequently includes coloboma.
When we diagnose coloboma, we may recommend screening for other health issues to ensure complete care. This is especially important in children, as early detection of associated conditions improves outcomes.
If your child has been diagnosed with coloboma, you may wonder about the risk for future children. Genetic counseling can help you understand the specific situation in your family. If the coloboma is part of a known genetic syndrome, the recurrence risk may be predictable based on the inheritance pattern.
For isolated coloboma without an identified syndrome, the recurrence risk is generally low but not zero. We may recommend genetic testing to look for specific changes that could affect family planning decisions and help other family members understand their own risks.
How We Diagnose Coloboma
When you come in for an evaluation, we start by asking about any vision problems you or your child have noticed and review your family and medical history. We check how well each eye can see using age-appropriate vision tests, which might involve reading letters, identifying pictures, or watching how an infant responds to visual targets. We measure intraocular pressure, check ocular alignment, and perform a cycloplegic refraction to determine an accurate glasses prescription.
We also examine the external appearance of the eyes, looking for differences in size, shape, or pupil appearance. These initial observations often reveal iris colobomas and other visible abnormalities that guide the rest of the examination.
A dilated eye exam is essential for diagnosing coloboma fully. We use special drops to widen your pupils, which allows us to see the entire retina, choroid, and optic nerve at the back of the eye. This reveals colobomas that are not visible from the outside and helps us assess the extent and location of any missing tissue.
We may also use imaging technology to document and measure the coloboma. Optical coherence tomography creates detailed cross-sectional images of the retina. Fundus photography captures color pictures of the back of your eye. Ultrasound may be used if we cannot get a clear view through the pupil or if we need to evaluate the overall structure of the eye.
Additional testing may include visual field testing, axial length measurement, widefield fundus imaging, fluorescein angiography or OCT-angiography for vascular assessment, electroretinography and visual evoked potentials in severe or atypical cases, B-scan ultrasonography for microphthalmia or poor view, and ultrasound biomicroscopy to evaluate anterior segment structures.
Genetic testing can identify specific gene changes responsible for coloboma in some cases. We may recommend this testing if there is a family history of coloboma, if other family members wish to know their risk, or if we suspect a genetic syndrome. A blood sample or cheek swab is typically all that is needed. Depending on the presentation, testing may include chromosomal microarray or exome-based panels.
Meeting with a genetic counselor helps you understand test results, inheritance patterns, and what the diagnosis means for your family. This professional can also discuss options for prenatal testing in future pregnancies if desired.
Because coloboma can be associated with other health conditions, we often suggest a comprehensive evaluation. This may include hearing tests, kidney ultrasounds, heart evaluations, and developmental assessments, especially in young children. Coordination with your primary care doctor and specialists ensures that all potential issues are identified early.
- Hearing evaluation by an audiologist
- Kidney and urinary tract imaging
- Cardiac examination and echocardiogram if indicated
- Developmental and neurological assessment
- Endocrine evaluation if growth concerns are present
- Ear, nose, and throat evaluation for choanal atresia or airway concerns when syndromic features are suspected
Treatment and Correction Options
Not all colobomas require active treatment. If your vision is stable and the coloboma is not causing significant problems, we may recommend regular monitoring to watch for any changes. These check-ups allow us to catch complications early and adjust your care plan as needed.
The frequency of your visits depends on the type and severity of the coloboma. Children typically need more frequent exams during growth periods, while adults with stable colobomas may be seen annually or as symptoms warrant.
If you have refractive errors like nearsightedness, farsightedness, or astigmatism along with your coloboma, glasses or contact lenses can improve your vision significantly. Prescription lenses help focus light properly on the retina, making the most of the functional vision you have.
Special tinted lenses can reduce light sensitivity and glare, which are common problems for people with iris colobomas. Contact lenses with painted irises are available for cosmetic purposes and can also help control the amount of light entering the eye if the iris cannot do this naturally. Scleral lenses and custom prosthetic-tinted contact lenses can improve comfort, reduce glare, and enhance cosmesis in selected cases. If you have functional vision in only one eye, we recommend full-time impact-resistant polycarbonate eyewear for protection.
Children with unilateral or asymmetric coloboma are at high risk for amblyopia. Early correction of refractive error, occlusion therapy with patching or atropine penalization, and timely strabismus management can improve visual outcomes.
- Full-time glasses for anisometropia and astigmatism
- Patching or atropine penalization per age-appropriate protocols
- Prism or strabismus surgery when indicated
- Close monitoring to adjust therapy as the child grows
Surgery to repair an iris coloboma may be considered if light sensitivity is severe and affecting your quality of life, or for cosmetic reasons. The procedure involves stitching the edges of the iris gap together to create a more normal pupil shape and reduce glare. We typically recommend this only when the benefits clearly outweigh the surgical risks. In selected cases, custom artificial iris implants may be used, often in combination with cataract surgery, with careful counseling about risks and benefits.
Results vary depending on the size and location of the coloboma. The surgery can improve light sensitivity and appearance, but it does not restore vision if the retina or optic nerve is also affected.
People with chorioretinal colobomas face an increased risk of retinal detachment, where the retina pulls away from the back of the eye. If this occurs, we may recommend surgery to reattach the retina and prevent permanent vision loss. The specific surgical approach depends on the location and extent of the detachment.
Other complications and their management may include:
- Prophylactic laser retinopexy at the border of the coloboma in selected patients to reduce detachment risk, based on individual anatomy and specialist judgment
- Glaucoma management with medications, laser, or surgery
- Cataract surgery when visually significant, with modified techniques in microphthalmic eyes
- Treatment of choroidal neovascularization if it develops
- Management of colobomatous cysts in severe microphthalmia
We address each complication with targeted treatments that align with current best practices, always prioritizing the preservation of useful vision.
It is important to understand that we cannot replace missing eye tissue or create new retinal cells where none exist. Surgery and other treatments can manage complications, reduce symptoms, and optimize the vision you have, but they cannot cure coloboma or restore vision lost due to missing retinal or optic nerve tissue.
Our goal is to maximize your functional vision and quality of life with the eye structure you have. Many people with coloboma live full, active lives by using the treatments and aids available to make the most of their remaining vision. Outcomes vary widely and depend on whether the macula and optic nerve are involved.
Living with Coloboma
Light sensitivity is one of the most common challenges for people with coloboma, especially if the iris is affected. Wearing wrap-around sunglasses or photochromic lenses that darken in bright light can make outdoor activities more comfortable. Indoors, you might benefit from adjustable lighting and avoiding glare from windows and shiny surfaces.
- Hats with brims to shade your eyes from overhead light
- Polarized sunglasses to reduce reflected glare
- Dimmer switches and adjustable lamps at home
- Screen filters for computers and tablets
- Task-specific filter tints, such as FL-41, trialed under professional guidance
If your coloboma causes significant vision loss, low vision aids can help you maintain independence. Magnifiers, both handheld and electronic, enlarge text and images for reading and other close work. Large-print materials, talking devices, and screen-reading software expand access to information and entertainment.
We may refer you to a low vision specialist who can recommend specific devices and teach you techniques to use your remaining vision most effectively. Many communities also offer orientation and mobility training to help you navigate safely. In some regions, bioptic telescopes may be considered for specific tasks, including driving where legally permitted.
Regular follow-up is critical for anyone with coloboma. Infants and young children should be seen at least annually, and more often if there are concerns about development or changes in vision. Adults with stable colobomas typically need yearly comprehensive exams, though we may recommend more frequent visits if you have had complications. Eyes with large chorioretinal colobomas or glaucoma risk may need more frequent visits for intraocular pressure checks and retinal evaluation.
These appointments allow us to monitor for retinal detachment, glaucoma, and other issues that can develop over time. Prompt detection and treatment of problems gives you the best chance of preserving your vision long-term.
Children with coloboma benefit from early intervention services that support visual and overall development. Low vision rehabilitation, early intervention services, occupational therapy, and educational support help your child learn to use their vision effectively and develop compensatory skills. Encouraging reading, puzzles, and activities that use fine motor skills strengthens visual abilities.
Work closely with your child's teachers to ensure appropriate classroom accommodations, such as preferential seating, enlarged materials, and extra time for visual tasks. Building your child's confidence and advocating for their needs sets the foundation for lifelong success. Request support from a Teacher of the Visually Impaired and consider a 504 plan or Individualized Education Program to formalize accommodations.
Frequently Asked Questions
Sometimes coloboma can be seen on a detailed prenatal ultrasound, especially if the affected eye is noticeably smaller or if the coloboma is part of a syndrome with other detectable features. However, many colobomas are too small or located in areas that ultrasound cannot visualize clearly, so they are not discovered until after birth during newborn examinations or later in infancy.
The coloboma itself, which is the gap in eye tissue, does not grow or worsen because it is a structural difference present from birth. However, complications such as retinal detachment or glaucoma can develop at any age, which is why ongoing monitoring throughout childhood and adulthood is essential.
Most cases are sporadic and cannot be prevented. Optimizing maternal health and avoiding alcohol during pregnancy are important for overall fetal development. Do not stop prescribed medications without consulting your clinicians.
Many children with coloboma can participate in sports, though we may recommend protective eyewear to guard the eyes from injury. Polycarbonate protective eyewear is recommended for any activity with risk of eye injury. Contact sports and activities with a high risk of eye trauma require extra caution, especially if your child has vision in only one eye. We can help you weigh the risks and benefits for specific activities based on your child's individual situation.
Coloboma can affect one or both eyes. Laterality and severity vary by type, with some forms more often unilateral and others more often bilateral.
Whether someone with coloboma can drive depends on their visual acuity and field of vision, not simply on having the condition. Many people with mild coloboma meet the vision requirements for a driver's license. Those with more significant vision loss may not qualify, but each state has its own standards, and we can help assess whether your older child or teen meets those criteria when the time comes.
Getting Help for Coloboma
If you or your child has been diagnosed with coloboma or you have noticed unusual pupil shape or vision problems, a comprehensive eye examination is the important next step. Your eye care professional can evaluate the extent of the condition, discuss your treatment options, and create a personalized plan to protect your vision and support your visual goals. Early and ongoing care makes a meaningful difference in outcomes for people living with coloboma.